DE3234598A1 - Method and device for controlling the dwell time of a continuous material in a heat-treatment device - Google Patents

Abstract

The method serves to control the dwell time of a continuous material (W) in a continually operating heat-treatment device (Sp). To achieve optimum material quality using measures which are relatively easy to carry out, the continuous material temperature is measured at measuring points in the individual device treatment areas by means of elementary sensors (15, 16) in the inflow region and the outflow region of circulating air, the temperature difference established being used as a standard for the transformation of energy on the continuous material to determine the heating of the continuous material. Depending upon this temperature measurement, a control is then effected of the transport speed of the continuous material in such a manner that the continuous material temperature exceeds a minimum temperature value during a predetermined dwell time. This control can be carried out quickly and automatically with great reliability. <IMAGE>

Description

3234Ö9 &

Method and device for regulating the dwell time of a material web in a heat treatment device

The invention relates to a method for regulation the dwell time of a material web in a continuously traversed by the material web, via its Length of treatment device divided into several treatment fields, according to the preamble of Claim 1. The invention also relates to an apparatus for carrying out a such procedure.

It is of particular importance for the heat treatment of textile material webs, for the most varied Types of goods to set and adhere to the optimal treatment temperature and time, if a high quality of the treated goods is to be achieved.

A large number of methods are now known from practice, according to which the heat treatment of the material web is monitored and controlled in the device intended for this according to various criteria.

Because with such a heat treatment, there are primarily several different properties of the material web (e.g. heat transfer values and basis weights) as well as the treatment temperature and the Transport speed within the treatment device play a role, it is for that Operating personnel of such a heat treatment apparatus extremely difficult to find the optimal one

Set and monitor treatment values correctly. Attempts have therefore already been made to monitor it and control or regulation of such a material web treatment semi-automatically or fully automatically to accomplish, then, for example, the treatment temperature in the device is readjusted during the web run.

These methods and devices known from practice are generally still proportionate Complicated measures and complex facilities are required in order to obtain a reliable one to be able to achieve automatic regulation.

The invention is therefore based on the object of providing a method as described in the preamble of claim 1 required type to create that is in comparison to known designs by its proportionate simple yet extremely effective regulatory measures and means and leads to optimal heat treatment results.

This object is achieved in that the web temperature at each measuring point in the device is measured indirectly by means of elementary transducers by using one each such a transducer, the circulating air on the one hand in the inflow area and on the other hand in the Measured outflow area of the circulating air and the determined temperature difference as a measure of the Energy consumption on the web to determine the

'6

web heating is used, and that the transport speed of the web depending on the temperature measurement on the specified dwell time at the specified Minimum temperature value is regulated.

With the aid of the transducers used according to the invention in the inflow area and in the outflow area the circulating air in each treatment field of the heat treatment device the web temperature can be measured indirectly, i.e. through the energy expenditure on the web, with simple Means and yet extremely reliable, so that you can always get an extremely accurate Immediate image of the temperature curve currently prevailing in each treatment field can get. The elementary transducers used here are relatively simple and robust in their structure and also largely maintenance-free.

Depending on the web temperature determined in this way -The material web transport speed can then be determined in an extremely simple manner set in such a way that the required dwell time of the material web within the heat treatment device as well as at the specified Minimum treatment temperature is guaranteed, whereby the specific, optimal heat treatment takes place for each type of goods can. These simple regulatory measures are also ideal conditions for a very

\ Reliable automatic operation of the heat treatment device.

A heat treatment device for performing this method is in particular in the form of a Tenter dryer formed, provided over the length of a number of treatment fields which work according to the air circulation principle.

IQ according to the invention is characterized, this heat treatment apparatus by the features specified in characterizing portion of claim 6 features.

Further details of the invention emerge from the subclaims and from the following description some exemplary embodiments explained in more detail with reference to the drawing. In this drawing demonstrate

1 shows a greatly simplified schematic representation

a heat treatment device having six treatment fields with associated electrical block diagram;

Fig. 2 is a simplified cross-sectional view

by the heat treatment device according to FIG. 1 to the arrangement of the measuring points to illustrate;

3Q Fig.3a, 3b, 3c a temperature profile diagram in the

Heat treatment device according to FIGS. 1 and 2, with the associated bar chart for displaying temperature

-β-

ι differences in the inflow and outflow air

in the individual fields;

4 shows a temperature profile diagram for explaining a second example.

With reference to Figures 1 and 2, let us first consider the design and arrangement of the measuring points as well as the design: facilities required for evaluating the measurement signals are explained using a simple example.

The heat treatment device is preferably formed by a tenter dryer (Sp), which basically in any number of treatment fields adapted for the respective application can be divided. In the assumed case, six treatment fields 1 to 6 are provided as well essentially similar and in the manner shown in the cross section according to FIG. 2 with treatment nozzles 8, 9 arranged above and below the web transport plane 7, as it is known per se. Each of these treatment fields 1 to 6 works according to what is known per se Circulating air principle, with a circulating air fan 11 in a common within the dryer housing 10 Inflow channel 12 of the treatment nozzles 8, 9 and before the intake duct 13 of the circulating air fan 11 Heat exchangers (radiators) 14 are arranged.

In each treatment field 1 to 6 formed in this way, the is in the inflow area and in the outflow area Circulating air, one elementary transducer 15 or 16 installed, with the transducer 16 in the area

the circulating air or return air flowing directly from the web W is arranged, during the Sensor 15 measures the supply air in the supply channel 12 between the circulating air fan 11 and nozzles 8, 9.

With the help of these elementary transducers 15, 16 in each treatment field 1 to 6 (or on each Measuring point) an indirect temperature measurement is carried out by measuring the energy consumption of the material web W by determining the temperature difference between supply air and return air depending on the heat consumption the web W is determined by water evaporation and heating of the goods.

The two transducers 15, 16 of each treatment field 1 to 6 are each assigned a temperature difference transducer 17 (see FIG. 1), and all of them Transducers 17 are in turn to one of the Tenter dryer Sp associated electronic computer 18 connected, which is a programmable microcomputer can act. All the required default data can be stored in this computer 18 so that it is suitable for the desired treatment temperature and treatment time as well as the dwell time, the required machine speed is determined immediately. This calculator 18 stands with a web transport effecting through the stenter dryer Sp, infinitely variable main drive 19 in such a way that each required Changes in the machine speed are transmitted immediately to the main drive 19 in terms of control is, whereby this in a corresponding way

can be provided.

The elementary transducers used here are relatively simple, have a robust structure have already proven themselves many times in other contexts and are largely maintenance-free. If in fact, should such a transducer fail, it can use a relatively can be replaced quickly at low cost. It is important for the described use this transducer as well as in the further processing of the measured values, however, "that through this indirect measurement of the temperature profile of the material web (through the energy conversion the material web) at any time an extremely precise image of the in each treatment field 1 to 6 or on every measuring point the current temperature curve can be displayed instantaneously.

The with the help of the transducers 15, 16 in each treatment field 1 to 6 determined temperature differences can be used to control and display the respective The prevailing temperature curves or the entire heat treatment process in diagram form can be used according to FIGS. 1a to 1c.

During the heat treatment of the textile web W, which is primarily a synthetic fiber web can act, it is assumed that this web of material continuously through the stenter dryer Sp is transported through. In Fig. 3b the longitudinal division of the stenter dryer Sp

in the treatment fields 1 to 6 shown in a more schematic form and in this case in correspondingly to the temperature profile diagram according to FIG. 3a and the bar diagram adapted according to FIG. 3c (cf. dashed lines). It is also assumed that the Synthetic fiber web is to be thermofixed in this stenter dryer Sp.

During the heat treatment in the stenter dryer Sp, the temperature of the web is measured at the measuring points provided in each treatment field 1 to 6 with the aid of the measuring transducers 15, 16. For performed here heat setting the synthetic fiber web which enters dry in the tenter dryer Sp, a specific type of product for this minimum temperature value is specified which is to lie in the diagram of Fig. 3a at about 18O ⁰ C. If one now looks at the course of curve I in FIG. 3a, it can be determined that, at a certain transport speed of the web of material, the predetermined minimum temperature value after the second treatment field 2 in the tenter dryer Sp

25 'is reached, i.e. by measuring the web temperature The spatial position of the point χ is determined over the entire length of the dryer, at which the web temperature has reached the specified minimum temperature value. At the for the curve I in Fig. 3a assumed transport speed of the web then remains within the total treatment time t in the tenter

dryer still has a dwell time of the material web from point χ to the end of the dryer, this dwell time corresponds to the passage time of the material web through the four treatment fields 3 to 6, as indicated _{in Fig. 3a with L χ.} This passage time of the material web from point χ to the end of the stenter dryer is then the dwell time of the material web at the specified minimum temperature value. The ones after the point χ

IQ curve I, which rises slightly, shows that the temperature of the material web continues to rise during the dwell time explained in the dryer. In the longitudinal section of the dryer in front of the spatial point χ, on the other hand, the material web is heated, so that in the temperature profile diagram according to FIG. 3a in the area before point χ the heating time is used.

As already indicated above, a specific heat treatment is required for each type of goods, in order to be able to achieve optimal quality results. Is now when changing the Type of goods or determined by ongoing monitoring or measuring at the individual measuring points, that with the temperature profile according to curve I in Fig. 3a - with the just existing Machine speed - the throughput time of the web from the mentioned point χ to the end or the outlet of the stenter dryer Sp is less than the specified dwell time, then the Machine speed reduced so much and thereby the spatial position of point χ (on the

Length of the dryer) until the throughput time of the web from this new point to the end of the dryer corresponds to the specified dwell time. With regard to the temperature profile diagram according to FIG. 3a, this means that by reducing the machine speed, the material web has already reached the predetermined minimum temperature value approximately in the middle area of the second treatment field 2; the spatial position of point χ in the dryer has thus moved forward, as indicated by point X ₁₁ in FIG. 3a. This forward shifting of the spatial position of the point χ thus results in a longer throughput time L of the material web from the new point χ II to the end of the dryer, this longer throughput time L __ corresponding to the specified dwell time. The heat treatment resulting from this dwell time and machine speed is shown by curve II in FIG. 3a, ie the material web treated in this case is heated more than that described in the first example (curve I).

The opposite is true if - again based on the machine speed at a Material line treatment according to curve I - the throughput time of the material line from point χ is greater than that predetermined dwell time. In this case, the machine speed is increased so much and thereby the spatial position of the point χ in the stenter dryer Sp so far to the rear

postponed (to point xIII) until the lead time L __ of the web from this new point xIII to the end of the dryer then the specified Corresponds to residence time. The resulting heat treatment of the web is through the curve III in Fig.3a illustrates after the warm-up time of the material web up to the specified minimum temperature value then up to the end of the third dryer treatment field 3 and the web then during the dwell time is heated less than in the previous examples according to curves I and III in Fig. 3a.

In all three previously described heat treatment examples for webs of material, the dwell time is Constantly regulated despite the variable machine speed.

The temperature differences determined during such a heat treatment with the aid of the transducers 15, 16 can then be reproduced in the form of a bar chart according to FIG. 3c and possibly can be displayed on a video screen, giving you an exact overview at all times the temperature profiles or des entire heat treatment process. The bar diagram according to FIG. 3c is adapted to the treatment sequences according to FIGS. 3a and 3b.

The bar diagram shows that the greatest temperature differences are at the measuring points or in

_ i C -

the treatment fields (e.g. 1 and 2) can be determined where the main heating or heating of the web takes place. The determined with the help of the transducers 15, 16 Temperature differences decrease when the specified minimum temperature value is reached, until they reach the optimum treatment temperature (e.g. fixing temperature), which is identical to the hot air temperature becomes practically zero, as can be seen from the bar graph 3c in the area of the treatment fields 4, 5 and 6 results.

In any case, however, the method explained above with reference to FIGS. 1 to 3 can be used in the tenter dryer Sp can be carried out automatically in an optimal manner, with necessary changes in the transport speed of the The web of material is recorded instantaneously and via the computer 18

can be immediately forwarded to the main drive 19 of the dryer in terms of control to the Web transport speed in adaptation to the specified dwell time at a specified minimum temperature value to adjust.

The described method is therefore extremely suitable for heat setting a synthetic fiber web, because this method allows the fusing temperature profile to be adhered to extremely precisely can. However, it should also be noted that others

Textlien appropriate heat treatments of / material webs in can be carried out in the same way and with similar precision, for example drying a material web or - which often happens in practice - the combination of drying and fixing, i.e. in the first section of the treatment device a wet or moist applied web of material is used first dried and then heat-set in the second device section.

A further simplified method for regulating the dwell time of a material web in the material web treatment device be based on the following example as well as another

25- based on the temperature progress diagram shown in FIG. 4, in which the total treatment time in the heat treatment device is again indicated on the abscissa with t and the web temperature reached (in ⁰ C) is indicated on the ordinate. The heat treatment device itself can be formed in a similar manner, as explained above, by a tenter dryer with a plurality of treatment fields

will.

In this case as well, the web temperature is preferred at a number of over the length of the device measured at distributed measuring points. It is assumed here that the at measuring point A within the actual temperature value determined by the device is selected so that it corresponds to a predetermined temperature setpoint value this measuring point A is compared. The measuring point A is constant in this example (and the same This also applies to the remaining parts distributed over the length of the heat treatment device, but in FIG. 4 measuring points not shown in more detail) ..

Considering in the temperature history chart of Figure 4, first the course of the temperature curve a with the proviso that the predetermined desired value (corresponding to the predetermined minimum temperature of the web) is χ in the item (in this case, ie at about 18O ⁰ C), then It is to be noted that in the case of a heat treatment of the material web according to the temperature profile according to curve a, the actual temperature value χ measured at measuring point A is still

is well below the specified minimum temperature value. In this case (curve a) the material line is treated for too short a dwell time at the required minimum temperature. At least about them required dwell time of the material web within the heat treatment device to achieve can, so the transport speed of the web must be reduced.

In the temperature profile according to curve b in Fig. 4 the specified minimum temperature value (point x) is now reached exactly at measuring point A / i.e. the measured actual temperature value corresponds exactly to the specified target value. In the case of the temperature profile according to curve b, there is also the throughput time of the material web from the selected measuring point A to the end of the heat treatment device - ' exactly the same as the specified dwell time. These minimum values for temperature and dwell time can also be used for many types of goods are not yet sufficient to achieve optimal goods quality. One Optimization of the heat treatment can be achieved if the transport speed of the material web is reduced even further, so that the temperature curve c in Figure 4 can result. The actual temperature value χ then determined at the selected measuring point A is in comparison to the preset value Minimum temperature value χ then slightly higher, so that the web temperature is further reduced Transport speed according to curve c is slightly above the minimum temperature value and also the throughput time of the web from measuring point A to the end of the device is somewhat longer than that specified minimum dwell time.

In this control method explained with reference to FIG is therefore determined with the help of the measuring point A, so to speak, a guide measuring point, and it is the specified web temperature - via the energy turnover minimum - constantly regulated at this point.

In comparison to that described with reference to FIGS. 1 to 3c In the first embodiment, it is preferred in this simplified variant of the method (FIG. 4), Instead of using an electronic computer, just use a simple controller that controls the system the selected measuring point A. At this selected measuring point A, the desired target value is set.

With regard to the various embodiments of the method according to the invention it should also be pointed out that even with automatic operation a switch to manual operation can be provided. This is fooling itself especially when starting the heat treatment device to the necessary treatment temperature and -speed very beneficial. After this start-up, automatic control can then be used be switched. These switching options from automatic to manual operation are also available also an advantage in the event of any malfunctions.

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Claims (6)

Diving. Dr. jur. VOLKMAR TETZNER van-Gogh-straße 3 8000 MUNICH 71 LAWYER and PATENT ADVERTISER Telephone; m) 798803 telegrams: "Tetznerpatent Munich" Telex: S 212 282 pate d Br 5257 claims: 1. Procedure for regulating the residence time of a Material web in one continuously traversed by the material web, along its length into several Treatment field subdivided heat treatment device, the heat treatment within the device is carried out by circulating air and the temperature of the material web measured in each treatment field at measuring points and the material web after reaching one predetermined minimum temperature value during a predetermined dwell time at least this minimum temperature value is maintained, characterized, that the web temperature at each measuring point in the device by means of elementary transducers is measured indirectly by using such a transducer each circulating Circulating air measured in the inflow area on the one hand and in the outflow area of the circulating air on the other the determined temperature difference as a measure of the energy expenditure on the material web for determination the web heating that has taken place is used, and that the transport speed of the material web depending on the temperature measurement to the specified dwell time at the predetermined minimum temperature value is regulated. 2. The method according to claim 1, characterized in that that by measuring the fabric web temperature on the length of the heat treatment device distributed measuring points the spatial position of that point is determined at which the The temperature of the web has reached the specified minimum temperature value, and that the transport speed the material web is regulated so that the throughput time of the material web from this point to the end of the heat treatment device corresponds to the specified dwell time. 3. The method according to claim 1, characterized in that the determined at a selected point The actual temperature value is compared with the minimum temperature value and the transport speed the web is controlled so that on the one hand the actual temperature value at least corresponds to the minimum temperature value and, on the other hand, the transit time of the material web from this selected measuring point to the end of the heat treatment device is at least equal to the specified dwell time. 4. The method according to at least one of the preceding Claims, characterized in that the temperature measurement signals received from each measuring point processed in a programmable electronic computer, from which the transport speed of the material web as a function of the measured Web temperature and the specified minimum temperature value is controlled. 5. The method according to at least one of the preceding claims, characterized in that the preferably formed by a synthetic fiber web ■ in the heat treatment device is dried and / or heat-set. 10 6. Heat treatment device, in particular stenter dryer, to carry out the method according to any one of claims 1 to 5, wherein over the Length of the device a number of treatment fields is provided, depending on the air circulation principle work, characterized in that in each treatment field (1 to 6) in the inflow and an elementary transducer (15, 16) is arranged in each case in the outflow area of the circulating air, both of which are arranged Transmitter of each treatment field to a common temperature difference transducer (17) connected and this temperature difference transducer in turn to one of the treatment device (Sp) associated, programmable electronic computer (18) are connected to the with an infinitely variable main drive (19) which effects the web transport Device is in control connection.